The present invention relates generally to medical instruments. More particularly, it relates to external pressure applicators and methods for administering eyedrop medicine. The lacrimal canaliculi (also known as tear ducts) allow tears to flow from the eye surface into the lacrimal sac and subsequently into the nasolacrimal ducts and exit through the nose into the back of the throat. The distal part of the nasolacrimal ducts are encased in bone and pressure on the skin external to that part will not impede tear drainage. Applying small pressure on the skin over any other part of the tear drainage path can effectively block tear drainage into the rest of the system. When administering eyedrop medicine on the eye, blocking this drainage path (also known as punctal occlusion) for a few minutes will enable the eye to fully absorb the medicine.
The current method of administering short-term punctal occlusion is to have the patient use a finger to press down upon the skin overlying the lacrimal canaliculi, lacrimal sac, and/or superior portion of the nasolacrimal ducts. Ophthalmologists typically prescribe 5 minutes of pressing time per eyedrop application. For example, when glaucoma patients are treated with multiple types of eyedrops, a 5 minute pressing time for each type of eyedrop would add up to a long duration of 15-20 minutes. Holding the finger for such a long duration is uncomfortable and not practical for most people. Consequently, patients seldom follow this practice as prescribed, thereby decreasing the efficacy of the treatment. Another issue is that patients seldom know exactly where the correct pressing point is located. Pressing on an incorrect area will not close the tear drainage path and therefore will not stop the eyedrop flow into the rest of tear drainage system. As a result, the retention time of eyedrop on the eye and effectiveness of the medicine is sub-optimal. This problem limits optimal treatment response leading to unnecessary prescription of additional medications, worsening disease, and risks of expensive eye surgery.
Punctal Occlusion plugs are disclosed in U.S. Pat. Nos. 6,994,684, 6,290,684, 5,830,171, 5,723,005, 5,334,137, and 5,283,063. However, all these patents involve some invasive procedures that may not be administered by patients alone. The subject matter of noninvasive external punctal occlusion is disclosed in the following patents:
U.S. Pat. No. 5,515,872 to Martin et al. discloses a clamp for placing over the nose bridge prior to ocular medication, to seal the nasolacrimal sac to prevent drainage of medication away from the eye. The clamp is positioned by a flexible molded nose cover. In one embodiment, the clamp is attached to eyeglasses designed to accept eyedrop applied to the eye. Subsequently, U.S. Pat. No. 5,832,930 was filed that added modified eyeglass frame and elastic fastening bands.
U.S. Pat. No. 5,522,837 to Latina discloses a U-shape device, with a bulbous element on the end of each leg that performs the similar function as the nose clamp except it requires hand positioning and pushing. The said device also has a pair of tubes attached to it to channel the eyedrop onto the eyes.
The nose clamp has its limitation as it may be difficult to clamp on a shallow or flat nose bridge. Positioning the pressure point right on the tear drainage path is the key to effective punctal occlusion. The flexible molded positioning device associated with the nose clamp may have difficulty to fit on the exact location on the nose as the nose boundary is somewhat fuzzy. The U-shape pressing device depends on patients to put the device on the right spot. The Martin clamp and Latina U-shape device would in no way suggest the device of this invention because they compress the nasolacrimal sac or nasolacrimal ducts on the nose rather than lacrimal canaliculi on the orbital rims.
To assure the punctal occlusion device functioning properly, a method is needed to calibrate the occlusion pressure and to verify the occlusion effectiveness. None of the prior patents disclose such method. Furthermore, it is desirable to enable patients to resume normal life activities while using the device such as wearing glasses or driving a car. None of the prior devices offer such capability.
In addition to the said punctal occlusion, there is a need to assure that the eyedrop goes into the eye. The methods and devices disclosed in the prior patents rely on passive devices to guide the eyedrop and the passive devices may come in contact with the eyedrop. A better way to guide the eyedrop is to enable the patients to see the position of the eyedrop bottle and thereby to actively aim the tip of the eyedrop bottle at the eyes.
The herein disclosed invention overcomes all the above limitations of prior devices